CVS commit: src/sys/arch/xen/xen

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Sat Feb 25 00:33:27 UTC 2023

Modified Files:
        src/sys/arch/xen/xen: xencons.c

Log Message:
xencons(4): Membar audit.

- xenconscn_getc: Once we have consumed an input slot, it is clearer
  to issue xen_wmb (release, i.e., load/store-before-store) before
  advancing in_cons so that the update becomes a store-release
  freeing the input slot for the other side to reuse.

- xenconscn_putc: After filling an output slot, must issue xen_wmb
  (release, i.e., load/store-before-store) before advancing out_prod,
  and another one before notifying the other side of the advance.


To generate a diff of this commit:
cvs rdiff -u -r1.50 -r1.51 src/sys/arch/xen/xen/xencons.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.